Big data is an evolving term that describes any voluminous amount of structured, semi-structured and unstructured data that has the potential to be mined for
information. Although big data doesn't refer to any specific quantity, the term is often used when speaking about petabytes and exabytes of data.
Big data analytics is often associated with cloud computing because the analysis of large data sets in real-time requires a platform like Hadoop to store large data sets across a distributed cluster and MapReduce to coordinate, combine and process data from multiple sources.
Although the demand for big data analyticsis high, there is currently a shortage of data scientists and other analysts who have experience working with big data in a distributed, open source environment. In the enterprise, vendors have responded to this shortage by creating Hadoop appliances to help companies take advantage of the semi-structured and unstructured data they own.